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Annotation of loncom/homework/templates/Rnumerical.problem, revision 1.1

1.1     ! www         1: <problem>
        !             2: <script type="loncapa/perl">
        !             3: $seed=&random(1,500,1);
        !             4: $n=&random(15,25,1);
        !             5: $offset=&random(2,5,0.1);
        !             6: $slope=&random(0.6,2.5,0.1);
        !             7: # construct a data set using R
        !             8: $data=&cas('R',"set.seed($seed);x<-1:$n;w<-1+sqrt(x)/2;data.frame(x=x,y=$offset+$slope*x+rnorm(x)*w);");
        !             9: # separate into an x and a y vector
        !            10: @datatable=split(/\s+/gs,$data);
        !            11: for ($i=0;$i<2*$n;$i+=2) {
        !            12:     push(@x,$datatable[$i]);
        !            13:     push(@y,$datatable[$i+1]);
        !            14: }
        !            15: $datax=join(',',@x);
        !            16: $datay=join(',',@y);
        !            17: # calculate the right answer using R
        !            18: ($intercept,$slope)=split(/\s+/,&cas('R',"x<-c($datax);y<-c($datay);dataset<-data.frame(x=x,y=y);fm<-lm(y~x,data=dataset);array(coef(fm),dim=2);"));
        !            19: $answer="$slope*x+$intercept";
        !            20: </script>
        !            21: <gnuplot width="400" solid="0" plotcolor="monochrome" gridlayer="off" bmargin="default" font="9" alttag="dynamically generated plot" bgcolor="xffffff" texfont="22" transparent="off" plottype="Cartesian" rmargin="default" gridtype="Cartesian" minor_ticscale="0.5" fontface="sans-serif" grid="on" align="right" texwidth="93" height="300" border="on" samples="100" fgcolor="x000000" major_ticscale="1" tmargin="default" lmargin="default" fillstyle="empty">
        !            22:     <curve linestyle="points" linetype="solid" color="x000000" pointtype="3" limit="closed" pointsize="2" linewidth="1">
        !            23:         <data>@x</data>
        !            24:         <data>@y</data>
        !            25:     </curve>
        !            26:     
        !            27: </gnuplot>
        !            28: 
        !            29: <startouttext />
        !            30: Consider the data set
        !            31: <pre>$data</pre>
        !            32: 
        !            33: Give a linear function approximating the data.<br />
        !            34: <tt>y(x)=</tt>
        !            35: <endouttext />
        !            36: <formularesponse answer="$answer" samples="x@1:$n#20">
        !            37:     <responseparam name="tol" default="2%" description="Numerical Tolerance" type="tolerance" />
        !            38:     <textline size="25" readonly="no" />
        !            39:     
        !            40: </formularesponse>
        !            41: </problem>